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课件网) Chapter 14 Chemical Kinetics Chemical Kinetics 14 14.1 Reaction Rates 14.2 Collision Theory of Chemical Reactions 14.3 Measuring Reaction Progress and Expressing Reaction Rate Average Reaction Rate Instantaneous Rate Stoichiometry and Reaction Rate 14.4 Dependence of Reaction Rate on Reactant Concentration The Rate Law Experimental Determination of the Rate Law 14.5 Dependence of Reactant Concentration on Time First-Order Reactions Second-Order Reactions 14.6 Dependence of Reaction Rate on Temperature The Arrhenius Equation Chemical Kinetics 14 14.7 Reaction Mechanisms Elementary Reactions Rate-Determining Step Experimental Support for Reaction Mechanisms 14.6 Catalysis Heterogeneous Catalysis Homogeneous Catalysis Enzymes: Biological Catalysts Reaction Rates 14.1 Chemical kinetics is the study of how fast reactions take place. Some happen almost instantaneously, while others can take millions of years. Increasing the rate of a reaction is important to many industrial processes. Collision Theory of Chemical Reactions Most reactions happen faster at higher temperature. Chemical reactions generally occur as a result of collisions between reacting molecules. According to collision theory of chemical kinetics, the reaction rate is directly proportional to the number of molecular collisions per second: 14.2 Collisions that result in a chemical reaction are called effective collisions. The activation energy (Ea ) is the minimum amount of energy required to initiate a chemical reaction. Molecules must also be oriented in a way that favors reaction. Cl + NOCl → Cl2 + NO Collision Theory of Chemical Reactions An effective collision results in reaction. Correct orientation to facilitate reaction Collisions that result in a chemical reaction are called effective collisions. The activation energy (Ea ) is the minimum amount of energy required to initiate a chemical reaction. Molecules must also be oriented in a way that favors reaction. Cl + NOCl → Cl2 + NO An ineffective collision results in no reaction. Incorrect orientation does not favor reaction Collision Theory of Chemical Reactions When molecules collide in an effective collision, they form an activated complex (also called the transition state). Collision Theory of Chemical Reactions Measuring Reaction Progress and Expressing Reaction Rate Chemical kinetics is the study of how fast reactions take place. 14.3 A → B [A] decreases Measuring Reaction Progress and Expressing Reaction Rate A → B Br2(aq) + HCOOH(aq) → 2Br–(aq) + 2H+(aq) + CO2(g) Measuring Reaction Progress and Expressing Reaction Rate Measuring Reaction Progress and Expressing Reaction Rate Br2(aq) + HCOOH(aq) → 2Br–(aq) + 2H+(aq) + CO2(g) Measuring Reaction Progress and Expressing Reaction Rate Br2(aq) + HCOOH(aq) → 2Br–(aq) + 2H+(aq) + CO2(g) Measuring Reaction Progress and Expressing Reaction Rate Br2(aq) + HCOOH(aq) → 2Br–(aq) + 2H+(aq) + CO2(g) First 50 second ... ...
